Starbucks isn't just the world's largest coffee chain, it's also a bellwether stock.

It tells us a lot about what's happening in the US and global economy, and what might be coming ahead in the future.

So what is Starbucks telling us?

Well, we've received recently some disturbing and somewhat surprising news from this company.

They're telling us that they're not going to be able to continue growing at a fast rate into 2020.

Donald Trump's Tax cuts and share buybacks

One of the biggest factors in their success in the last couple of years has been the Trump tax cuts.

Those are running out.

And so the company is struggling to achieve the same kind of 10% year on year growth they had seen before in earnings per share.

What are they going to do now?

Well, one of the things that Starbucks is doing, which is very indicative of a larger trend in corporate America, is share buybacks.

They are pulling forward a large number of share buybacks that they were expecting to do in 2020, in order to continue buoying those results.

And this really speaks to the fact that corporate America has been doing a shell game in the last two years of issuing debt - cheap debt - debt load at Starbucks has increased threefold in the last couple of years, and then using that debt to buy back their own shares in order to buoy the price.

Now, this always works because they're artificially reducing the number of shares on the market, but a lot of people, like me, feel that it doesn't really represent a buy into a growth story.

Share buybacks are not done best at the top of a market, but really at the bottom of a market.

Which really says to me that this is not a bet on future growth of a stock, but rather an attempt to manufacture a story for the street.

What does that tell us about corporate America and consumer trends?

Right now we have stocks as expensive as they've been in the US for 150 years and yet companies are still continuing this game of issuing debt, buying back shares and trying to keep stocks up.

Now, Starbucks tells us that they think that the US consumer is still buoyant.

That's important because many people, including the New York Fed chair, Rob Kaplan at the Dallas Fed, believe that the US consumer is the one thing standing between the US and recession.

The question is how long can that buoyancy continue?

When is the US consumer gonna really feel that perhaps not all is well in corporate America?

Well, it could be that one bad jobs report, one bit of bad economic news, could topple that confidence.

And this puts me in mind of something that founder Howard Schultz told me a few years back.

I interviewed him in 2015 when the company was actually announcing very good results.

But he stood up in front of a number of Wall Street analysts and said that the US consumer is fragile.

That, since the great financial crisis, consumers have become skittish.

The first sign of bad news they will button up their wallets.

All we can do is hope for the sake of the US economy and the global economy that Starbucks's consumers and American consumers have had their double shot.